Industrial controllers are special-purpose computers utilized for controlling industrial processes, manufacturing equipment, and other factory automation, such as data collection or networked systems. Controllers often work in concert with other computer systems to form an environment whereby a majority of modern and automated manufacturing operations occur. These operations involve front-end processing of materials such as steel production to more intricate manufacturing processes such as automobile production that involves assembly of previously processed materials. Often such as in the case of automobiles, complex assemblies can be manufactured with high technology robotics assisting the industrial control process.
In many automated processes, including the basic production of commodities such as food, beverages, and pharmaceuticals, complex state logic is often designed and programmed by Systems Engineers or provided in some cases by automated equipment manufacturers. This logic is often programmed with common PLC ladder logic or higher level languages supported by Sequential Function Charts. Sequence logic can be employed for a plurality of tasks such as material movement and conveying operations, packaging operations, or as part of an assembly process itself, wherein various stages of an assembly are sequenced from stage to stage until a final assembly occurs. As can be appreciated, much planning and design is required to implement an automated production process that can involve hundreds of machines, computers, and program logic to facilitate proper operation of the respective sequences.
In modern systems, many layers of regulation are now being imposed on automated industries to ensure compliance to applicable standards. To document that these requirements are being adhered to, often one or more signatures are required which in some systems may be more than merely signing a journal record or document but, in increasing circumstances these procedures have become electronic. For instance, if a customer in an FDA regulated industry desires to use electronic signatures in place of handwritten signatures, they must do so in accordance with 21 CFR Part 11. In some existing systems, electronic signatures are only offered in association with report parameter verification in procedural phases, verification of procedural steps, and confirmation of batch and phase commands. However, these signatures may be lacking several key features required under 21 CFR Part 11. For example, the meanings of the signatures are not presented to the signers nor recorded, and in some electronic event journals it may be difficult or impossible to determine if an electronic signature was properly obtained or not.
Some of the notable aspects of 21 CFR Part 11 include:                (a) Signed electronic records shall contain information associated with the signing that clearly indicates all of the following:                    (1) The printed name of the signer;            (2) The date and time when the signature was executed; and            (3) The meaning (such as review, approval, responsibility, or authorship) associated with the signature.                        (b) The items identified in paragraphs (a)(1), (a)(2), and (a)(3) of this section shall be subject to the same controls as for electronic records and shall be included as part of any human readable form of the electronic record (such as electronic display or printout).        
In addition to the components mentioned above, customer requirements include the ability to specify one or more signers for each signature, to specify security requirements for each signer, and to specify a comment requirement for each signer.
Journaling requirements are further described in the following 21 CFR Part 11 excerpt:
“Electronic signatures and handwritten signatures executed to electronic records shall be linked to their respective electronic records to ensure that the signatures cannot be excised, copied, or otherwise transferred to falsify and electronic record by ordinary means.”
In view of the above, many modem industrial automation systems are not equipped to process, record, and document required signature activities. For instance, in a typical factory setting, process steps and operator actions requiring possible signature authentication are highly distributed throughout various locations in the factories. Attempting to manage such activities from various locations can be a challenge even for the most sophisticated of automation systems. Also, some systems providing crude attempts at signature verification may allow certain activities to occur such as alteration of a system parameter before the actual authentication of the signature has occurred.